Location tracking systems, such as the global positioning system (GPS), have provided the ability to accurately locate mobile devices in outdoor spaces. Unfortunately, these services perform poorly indoors when GPS signals are no longer available. Highly accurate indoor location tracking would enhance a wide variety of applications including: building navigation (malls, factories, airports), augmented reality, location-aware pervasive computing, targeted advertising and social networking.
Solutions have been proposed for locating object devices indoors involving beacons and transponders. However, these systems require the installation of many densely located infrastructure devices and require complicated additional hardware in the object device. It is desirable to locate an object device indoors without the need for additional hardware attached to the device being localized.